1. Field of the Invention
This invention is concerned with the formulation of polymerizable coating compositions. It is particularly directed to coating compositions useful for transfer coating application.
2. Description of the Prior Art
The transfer of coatings from carrying webs comprised of silicone release coated paper is well known. The application of this technique using electron beam curing on heat sensitive substrates is described in British Pat. No. 1,519,493.
We have found that radiation curable coatings differ in their adherence to the various plastic, metallic and paper substrates used in commerce. This led to the concept of utilizing this phenomenon to transfer a coating from one substrate having a relatively weak adhesive bond to a second substrate having a stronger bond, as disclosed in U.S. patent application Ser. No. 939,095, filed on Sept. 1, 1978 by L. A. Psaty, now abandoned; and a continuation in part thereof Ser. No. 967,188 filed Dec. 7, 1978 now abandoned.
This practical significance of this transfer coating concept is that low cost substrates readily availble in commerce may be substituted for the expensive release paper currently used as the carrying web for this purpose. Furthermore, the surface texture of the carrying web may be desirably imparted to the cured coating. In this way any of a number of aesthetically pleasing and decorative effects can be produced. In addition, when using a nonporous substrate as the carrying web for transfer of the coating composition to a porous substrate, the quantity of coating required is greatly reduced due to the minimization of wicking of the uncured coating into the porous substrate. The result is a coating which resides largely on the surface of the porous substrate, thus more easily bridging the irregularities of that surface with a minimum of coating material. A particularly good example of this process is the transfer of a coating composition from a polyester web to paper to provide a smooth glossy surface for subsequent vacuum metallization. The metallized surface obtained in this manner is exceptionally shiny and free from flaws and blemishes.